[kreutz]

Hello;

The Question is: What would you like to see on a UHU High Power Servo Drive?
(Multiple answers are OK)

1- Less than 185 Volts @ more than 25 Amps.
2- Higher than 185 Volts @ 25 amps or less.
3- higher than 1000 ppr encoder interface
4- higher than 150 K steps/sec
5- Allow the use of the intermittent torque region above Continuous Stall Current and under the Maximum (demagnetization) Current limit of the motor.
6- Other features (specify)

[Kipper]

Why do you ask...

[kreutz]

Why do you ask...

Long story short :

There is thread dedicated to the UHU controller ( http://www.cnczone.com/forums/showthread.php?t=14217 ).

For those who are not familiar with the above mentioned long thread; The UHU controller is a DIY Brushed DC servo control board with Step-direction interface. The original UHU controller has different PCB versions, and some of the users complained about overheating RC output filter at voltages over 80 volts, and sometimes power stage destruction.

I decided to take a look at the problem in order to help those users. The root cause was determined (and documented on the thread) to be cross conduction on the output stage, and a redesign was done in order to correct it. The newer version is called UHU HP, the schematics are provided (free) on the thread, some members are also providing it in a kit form (not for profit), since it is also a DIY version.

The UHU HP has a few features not available on the original UHU board, mainly related to improved safety in order to deal with higher voltages and currents (tested at 185 Vdc 25 Amps), and an experimental current limit circuit that allows the use (for a short time) of the intermittent torque area above the nominal maximum continuous Stall Current and below the Absolute Maximum Stall current. Nevertheless, most of the features, and some limitations, of this version are inherent to the "UHU chip" which is not open source, but is easily available (and cheap) from the original source in Germany ( http://www.uhu-servo.de/ ).

This poll was created in order to find out if extra modifications/customization would be useful and welcomed in this community, and to decide if dedicating more of my free time and resources to offer this service for free is going to be a loss of time and money .

Thanks,

Kreutz.

[Kipper]

IMHO and in way to detract from your statement, If you can improve a design then do so! I have no way of knowing if it is so! :shrug: I'm presuming "now" that you've seen the error and can circumvent the disaster that has befallen others? Anyone who gives freely of their time to help others gets my vote(there are many here) what's wrong with profit? I like profit...it makes me get out of bed.(wedge)

[kreutz]

IMHO and in way to detract from your statement, If you can improve a design then do so! I have no way of knowing if it is so! :shrug: I'm presuming "now" that you've seen the error and can circumvent the disaster that has befallen others? Anyone who gives freely of their time to help others gets my vote(there are many here) what's wrong with profit? I like profit...it makes me get out of bed.(wedge)

There is nothing wrong with doing it for profit. Nevertheless, the modifications were done for free, in order to harmonize with the spirit of the original UHU drive, whose schematics were posted that way, and because some of the members had already invested on their boards/parts, and their budget, as well as their faith on the possibility to make them work, was diminishing.

I am working on a newer, possibly the last, revision of the UHU HP board, and I would like to see if it is worthwhile to dedicate a little more time to provide extra features, or if a complete (from the ground up) design would be a better idea, the latter would probably be for profit if it ever becomes a reality... (just to show I have nothing against getting rich ).

Kreutz.

[rokag3]

hello,
i think that index position for this servo is a must since a lot of highpower uhu will be used for lathe spindle

[kreutz]

hello,
i think that index position for this servo is a must since a lot of highpower uhu will be used for lathe spindle

I will take it into account.

Thanks,

Kreutz.

[HJozsi]

hello,
i think that index position for this servo is a must since a lot of highpower uhu will be used for lathe spindle

Hi rokag3,

What kind of NC program do you use for lathe? Do you use 1:1 spindle pulley ratio only?

I use Mach3, but it does not expect spindle index signal from the spindle motor controller ( motor encoder). It expects index ( or timing ...) signal from an "encoder" (one pulse or four pulse in a rev.) mounted to the spindle (or with 1:1 ratio with pulley near the spindle, you can see in Mac3 Lathe doc)... Mach3 needs 4 pulse/rev "encoder" ( one of the pulses must be double wide ) if you want to make threads and check 'timing' in the input settings instead of 'index'...

Well I'm not familiar with other NC programs, others might do differently, that's why I'm asking ...

Regards,

Jozsi